Yamaha, Onkyo, and Denon are all well-designed receivers with amp sections capable of driving 8-ohm loads (or lower impedances) with no problem; I would check some of the features of each receiver for ease of operation, simplicity of on-screen menus (make sure the receiver you like has on-screen menus), and the ergonomics of the remote control. Without knowing your room size, it's hard to estimate whether the power output of each receiver is adequate. For all but the largest rooms however, any of the receivers you mention will have ample power for either the Grand Master or the Epic 40 home theater systems.
Alan Lofft
Resident Expert
